This invention relates thiophene-2-carboxamidotetrazoles which inhibit the effects of the Mac-1 leukocyte molecule, and as such are useful for treating diseases mediated thereby, including inflammatory disorders.
Leukocyte-endothelial interactions are involved in the pathogenesis of various inflammatory diseases. In an immune or inflammatory response, circulating neutrophils interact with the endothelium via their adhesion molecules. The adherence of the neutrophil to the endothelium, and the subsequent transendothelium migration to the site of injury or infection, is the normal host response. Unfortunately, in various disease states such a response can become too aggressive; the influx of neutrophils can cause damage to tissue, thereby causing chronic inflammation.
Cell adhesion molecules can be classified in a number of families, three of which are the integrins, the immunoglobulins, and the selectins. The integrins can be found on leukocytes and platelets. They bind to the immunoglobulin family on blood vessel endothelial cells.
The leukocyte adhesion molecule Mac-1 (CD11b/CD18) is a heterodimeric glycoprotein expressed on the plasma membrane of neutrophils and monocytes. Mac-1 is a member of the .beta..sub.2 subfamily of integrins. Interaction of upregulated Mac-1 on stimulated neutrophils with its ligands on endothelial cells plays an important role in the pathogenesis of numerous inflammatory disease states. The response of the neutrophil in host defense function depends on this type of adherence. The inflammatory response depends on neutrophil influx to the site of infection or injury. A rational target for therapeutic intervention thus is to inhibit the adhesion process. Drugs which inhibit the adhesion of leukocytes to the endothelium could be used as therapeutic agents in such conditions as ischemia, reperfusion, transplant rejection, ulcerative colitis, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and NSAID-induced gastropathy.
The binding of the denatured protein known as keyhole limpet hemocyanin (KLH) to human and canine neutrophils has been shown to be Mac-1 specific (J. Immunol., 144(7):2702-2711, April 1990). The binding of stimulated neutrophils (with fMLP) to KLH can be blocked with antibodies to Mac-1. An inhibition of the adhesion process using monoclonal antibodies has been shown to inhibit the inflammatory response in a model of lung injury (Rosen H., J. Leuk. Biol., 48-465 (1990); Mulligan M. S., et al., J. Immunol., 150:2401-2406 (1993)), and a canine model of myocardial ischemia/reperfusion injury (Simpson P. J., et al., Circulation, 81:226-237 (1990)). We have now discovered that small molecular weight thiophene-2-carboxamidotetrazoles also inhibit the adhesion of Mac-1 to KLH coated plates.
The role of leukocyte adhesion molecules in NSAID gastropathy has been well documented by John Wallace, et al., Gastroenterology, 100:878-883 (1991); Am. J. Physiol., 259:G462-G467 (1990). Neutrophil adherence to the endothelium is a critical pathogenic event in models of gastrointestinal ulceration. Anti-CD18 monoclonal antibody markedly reduced the severity of damage induced by indomethacin in the rat. Similar results were obtained with anti-ICAM. While these monoclonal antibodies have been found to inhibit the adhesion of Mac-1, the need continues to find small molecular weight organic molecules which are also effective. We have now found that the thiophene-2-carboxamidotetrazoles described below inhibit Mac-1 adhesion, and thereby are effective in treating diseases medicated thereby.
An object of this invention is thus to provide new compounds which are characterized as thiophene-2-carboxamidotetrazoles. The invention additionally provides a method for inhibiting the adhesion of Mac-1 in diseases mediated by such molecule. A further object is a method for treating diseases including NSAID-induced gastritis and ulceration, ischemia, reperfusion, ulcerative colitis, inflammatory bowel disease, rheumatoid arthritis, and multiple sclerosis.